Importing module with capsule attribute fails in sub interpreter

[tonybaloney]

Bug report

Bug description:

When importing certain modules (zoneinfo is an example), attributes are missing when inside a sub interpreter.

Importing these modules works inside the main interpreter.

I've written a test to demonstrate the bug

import unittest
import _xxsubinterpreters as interpreters


class TestCapsule(unittest.TestCase):

 def test_capsule(self):
 import zoneinfo

 def test_capsule_in_sub_interpreter(self):
 interp = interpreters.create()
 interpreters.run_string(interp, "import zoneinfo")

.Traceback (most recent call last):
 File "<string>", line 1, in <module>
 File "/usr/local/lib/python3.13/zoneinfo/__init__.py", line 14, in <module>
 from _zoneinfo import ZoneInfo
AttributeError: module 'datetime' has no attribute 'datetime_CAPI'
E
======================================================================
ERROR: test_capsule_in_sub_interpreter (test_capsule.TestCapsule.test_capsule_in_sub_interpreter)
----------------------------------------------------------------------
Traceback (most recent call last):
 File "/Users/anthonyshaw/projects/subinterpreter-web/test_capsule.py", line 12, in test_capsule_in_sub_interpreter
 interpreters.run_string(interp, "import zoneinfo")
_xxsubinterpreters.RunFailedError: AttributeError: module 'datetime' has no attribute 'datetime_CAPI'

----------------------------------------------------------------------
Ran 2 tests in 0.457s

FAILED (errors=1)

I haven't seen this behaviour on any other modules, the thing that seemed special with datetime and this attribute is that it is a PyCapsule. So the issue is likely related to that?

CPython versions tested on:

3.13, CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-112100 Verify that zoneinfo can be imported #112101

[tonybaloney]

@ericsnowcurrently this is one of the issues I've found trying to run Django inside a sub interpreter

[tonybaloney]

This is the specific line that's failing. https://github.com/python/cpython/blob/main/Modules/_zoneinfo.c#L2717

The _zoneinfo module runs PyDateTimeAPI = (PyDateTime_CAPI *)PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0) which fails.

There is no check for whether the datetime module has been imported and is initialised.

[Eclips4]

I'm not sure, but it's probably related to the fact that _datetime isn't isolated for subinterpreters yet: #102995.

[Eclips4]

This is the specific line that's failing. https://github.com/python/cpython/blob/main/Modules/_zoneinfo.c#L2717

The _zoneinfo module runs PyDateTimeAPI = (PyDateTime_CAPI *)PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0) which fails.

There is no check for whether the datetime module has been imported and is initialised.

PyCapsule_Import imports the datetime module.

[tonybaloney]

I'm not sure, but it's probably related to the fact that _datetime isn't isolated for subinterpreters yet: #102995.

Yep, looking at that PR and the related changes it would probably cause the behaviour I'm seeing in this test

[ericsnowcurrently]

@tonybaloney, could you verify if this is still a problem in 3.13?

[tonybaloney]

Just confirmed this test case was fixed since 3.13b1 (tested 3.13b3)